You might receive a Binary Rejection email from Apple after sending your iOS app for review, with a message regarding third-party login services, such as this:
Guideline 4.8 - Design - Sign in with Apple
To resolve this issue, please revise your app to offer Sign in with Apple as an equivalent login option.
To learn more, see the Sign in with Apple Overview.
On September 12, 2019, Apple added a new guideline to its App Store Review Guidelines, under Design, Guideline 4.8. Apple's new instruction requires all new apps that use a third-party or social login service to offer Apple Sign-in as an equivalent service.
For further details, you can look at Apple's Usage Guidelines for Websites and other Platforms.
- You are publishing an iOS application with the Sign-in feature enabled.
Apple does not allow authentication with third-party login services if sign in with Apple is not also included.
Our development team is working on a solution and is now in the process of releasing it.
Until then, you will not be able to use third-party login services on iOS applications. To this end, navigate on your app's Dashboard to Settings -> App Screens menu and disable these options.
After disabling third-party login services and republishing your application, you will not receive this error.